We begin tonight with american jobs. And a number we have not seen in nearly four years. Unemployment, now 7.8%. A surprising dip, dropping after 43 points above 8%. 114,000 new jobs added last month. And with it, 32 days now until the election. And your voice, your vote. Abc's david muir is here with us, right now. David? Reporter: Great to see you in person, diane. Not only were the jobs numbers a welcome sign for the americans lucky enough to get those jobs, they were very welcome by the president today, fighting to keep his job. And after that debate performance this week, tonight, that spring in his step is back. Bounding up to the podium, the new jobs numbers were more than just a economic jolt, they were a political one. Today, the president in the battleground of virginia. This morning, we found out that the unemployment rate has fallen to its lowest level since I took office. Reporter: Hours later, in the It's a reminder that this country's come too far to turn back now. Reporter: Today, after nearly four years of unemployment above 8%, what economists called a sharp drop. Down to that 7.8%, a psychological benchmark, broken. And a boost for the president, just days after his disappointing debate performance against a challenger who came ready. But you've been president four years. Reporter: For months now, central to mitt romney's stump speech, his lacer focus on unemployment above 8%. 40 straight months. Not been below 8% for 41. 42. 43 straight months with unemployment. Reporter: And just as romney travels to florida this weekend, a message from florida's republican governor before romney arrived. The governor tweeting about huge economic gains there. Tampa, st. Pete, clearwater and miami area experienced largest unemployment rate declines in the country. A tricky balance for the country, arking voters change course amid an improving picture. Romney emphatic it is not going quickly enough. The reason it's come down this year primarily due to the fact that more and more people have just stopped looking for work. Reporter: But economists say in this jobs report, that's not entirely the case. Some have dropped out, but there's been a surge in the number of baby boomers retiring. And there was more hiring in recent months than first thought. And romney working to win over voters who are out of work. Now offering this about those comments he made about the 47%. The americans, he said, he doesn't worry about, those he said he can't convince to take personal responsibility. Clearly, in a campaign with hundreds if not thousands of speeches and question/answer sessions, now and then you're going to say something that doesn't come out right. In this case, that's just completely wrong. Reporter: Now, all day there's been chatter among well-respected names that this number now below 8%, just weeks before the election, is, well, I asked the romney campaign late today if they believe the numbers are legitimate. One key adviser said they'll leave the speculation to others, that, quote, we'll deal with the numbers, diane, as they've been reported.

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